Audio forensics is the close examination of audio files for legal purposes. Audio forensic experts examine the recording in a forensics lab to confirm its authenticity and perform enhancement techniques to clarify its contents. The examination typically involves checking integrity, improving speech clarity, transcribing dialogue and reconstructing event timelines. 

How Audio Evidence Is Collected

Audio evidence collection must be performed per industry best practices. The Scientific Working Group on Digital Evidence (SWGDE) outlines acceptable methods for acquiring audio files for forensic analysis:

Forensic Audio Authentication and Analysis

After the evidence has been collected, the audio forensics expert will inspect the recording to determine its authenticity. In this digital age of advanced software editing, it is easy for an audio file to be tampered with, making it inauthentic. The expert will examine the recording using SWGDE best practices to determine if an audio file has integrity.


Audio files can also be enhanced to remove unwanted background noise so dialogue can be heard more clearly. Various filters are applied to the recording to achieve this, such as:

Frequency equalization

Equalizers cut or boost specific bands of frequency. The frequency bands that contain the most speech content — 600-3,000 hertz — can be isolated or amplified to make speech more intelligible. If there are loud background noises, a spectrum analyzer can be used to identify their frequency and reduce the noise with the equalizer.


If the speech or sounds in the recording are faint, the signal can be compressed to reduce the dynamic range and boost the softer sounds.

Specific Filters

We have a licensed arsenal of forensic software tools for specific applications like De-Reverb, De-Wind De-Hum and De-Crackle.

How Forensic Audiology Is Used in Court

Audio files that have been examined and clarified by an audio forensic expert can be used in court as evidence. The audio forensic scientist may serve as an expert witness and provide reports and testimony on the results of their investigation. The information they provide includes everything from their methodology to unbiased opinions on the results obtained. 

Digital Image Forensics and Expert Witness Services

Contact Primeau Forensics for Forensic Audio Services

For more than 35 years, Primeau Forensics has provided expert audio forensic services to litigators, law enforcement agencies and the U.S. government. We provide thorough analysis and expert testimony that you can count on to hold up in court. Contact us today to learn more about our services. 

For more information regarding audio forensics, please contact us for a pro bono consultation.

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